1. Field of the Invention
The present invention relates to a laser scanning unit (LSU) adopting a deflection disk, and more particularly, to a LSU adopting a deflection disk having a structure capable of radiating heat generated by a light source.
2. Description of the Related Art
In general, a LSU is a device which scans laser beams onto a photoreceptor so as to form a latent electrostatic image used for development. The LSU is widely used in an image output device which outputs an image by electrophotography and is divided into a rotary polygon mirror type and a deflection disk type according to the type of deflector adopted in the LSU.
Referring to FIG. 1, a conventional deflection disk type LSU includes a driving source 10 for providing a rotational force, a deflection disk 15 installed on a rotary shaft 11 of the driving source 10 and light sources 20 which are installed facing one surface of the deflection disk 15 at a predetermined angle and irradiate laser beams.
The deflection disk 15 consists of a plurality of sectors 15a each having a hologram pattern. The deflection disk generates as many scan lines as the number of sectors by being rotated once by the driving source 10.
The light irradiated by the light sources 20 is transmitted to the deflection disk 15 and is simultaneously deflected thereby to form scan lines. A semiconductor laser emitting laser beams of a predetermined wavelength is used for the light sources 20. Specifically, the laser irradiates light of various wavelengths depending on the change in the environment such as an increase in temperature. Accordingly, the directions of diffraction and deflection of the light change after passing through the deflection disk 15, so that the scan lines head in undesirable directions.